COMPARATIVE ANALYSIS OF GEODYNAMIC PARAMETERS OBTAINED FROM ASTRONOMIC AND GPS OBSERVATIONS IN POLTAVA

Abstract

The functioning of the GPS station and regular astrometric observations with a prismatic astrolabe in Poltava provides series of local displacements of the earth's crust and plumb line in time, characterizing the changes in the gravitational field. The analysis of the N-component of the earth's crust movement and the displacement of the meridional projection of the plumb line was carried out on the basis of GPS data and from observations on the astrolabe, respectively, for the period 2002-2020. Comparison of the trends of these series showed that their shifts occur in opposite directions. It is noted that the movement of the point occurs in the northern direction at a speed of +0.3mm/yr, and the displacement of the plumb line - to the south, at a speed of -2.6mas/year. Similarly, an abrupt displacement of the N-component to the north by + 2mm at the turn of 2014 was accompanied by a displacement of the plumb line to the south by approximately -50 mas. These facts can be explained within the framework of the hypothesis of the existence of a deep structure in the vicinity of Poltava, in which a significant change in mass occurs. The spectra of both series show the presence of cyclicities with close periods: about 3.2, 2.8, 1.0, 0.5, and 0.3 yr. It is known that harmonics with those periods are present in many astrometric series. The geodynamic interpretation of the presented facts requires additional confirmation in observations of neighboring GPS stations, as well as a theoretical explanation and justification.